TRF elevates while bombesin, neurotensin and beta-endorphin lower body temperature of rats when these peptides are given intracisternally. Studies are proposed to evaluate the possible role of TRF, bombesin, neurotensin and beta-endorphin in the central nervous system control of thermoregulation. Detailed gross and microanatomic distribution of these peptides will be determined using the brain micropunch technique with specific radioimmunoassays of peptides extracted from this tissue. Immunofluorescence studies will also be used to determine the precise localization of peptide producing cell bodies, axons and synapses. Specific sites of action of these peptides on thermoregulation will be determined by microinjection of peptide into specific brain areas. Assessment will also be made of the interaction of these peptides with cholinergic, serotonergic, dopaminergic and histaminergic agonists and antagonists to affect body temperature. Structure activity relationships of these peptides for synaptosomal binding and biologic action will be determined in binding studies and bioassays using structural analogs of each peptide. The effects of TRS on endogenous brain levels of bombesin, neurotensin and beta-endorphin, as well as the effects of bombesin, neurotensin and beta-endophin on brain levels of TRF is proposed. Possible physiologic relevance of these peptides to torpor will be evaluated in heterothermic endothermic mammals. We will measure endogenous levels of these peptides in the brains of ground squirrels during various stages of hibernation. Attempts will be made to induce torpor with bombesin, neurotensin and beta-endorphin and to reverse torpor with TRF. These studies may provide information fundamental towards implicating a role for CNS peptides in neurobiology. These studies may provide information basic to better treatment of disorders of thermoregulation in humans.